head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is variance, and it is a single point.

Execution · Pure Mechanics
The full-band rhythm game whose setlist and feel made it the genre's high-water mark.

Execution · Pure Mechanics
PaRappa spinoff guitar rhythm game with famously strict and slippery timing judgment.
Rock Band 2 leans Execution (Pure Mechanics); Um Jammer Lammy leans Execution (Pure Mechanics).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Rock Band 2
Guitar, drum, and vocal accuracy on expert charts
Um Jammer Lammy
Loose timing windows punish imprecise guitar inputs
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Rock Band 2
Charts never respond
Um Jammer Lammy
Call-and-response lines are scripted
Um Jammer Lammy leans a little harder on variance, though the gap is small.
Rock Band 2
Fixed setlist charts
Um Jammer Lammy
Fixed songs, ad-lib scoring slightly opaque
Rock Band 2 leans a little harder on optimization, though the gap is small.
Rock Band 2
Overdrive activation paths decide leaderboard scores
Um Jammer Lammy
Freestyle Cool-mode lines can be crafted and learned
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.